   (-> form zip/seq-zip zip/down zip/right arrow-line-number))
 
 
-(defn- basename [string]
-  (last (str/split string #"/")))
+(defn compile-time-fallback-position []
+  (list (current-file-name) @fallback-line-number))
 
 
 (defn current-file-name []

        :else
        (vary-meta form assoc :line (:line (meta number-source)))))


                 (zip/next line-loc)))))


(defmacro line-number-known
  "Guess the filename of a file position, but use the given line number."
  [number]
  `[(current-file-name) ~number])


(defn positioned-form
  "Make sure the form is annotated with a line number, either
   its original or the given one. Takes either a number or form
